The incident happened at the station in High Street, Sutton just after 10.20pm yesterday (September 7).
Officers and London Ambulance Service crews attended, however, a person was pronounced dead shortly after.
Trains between Sutton and Mitcham Eastfields were cancelled as the incident was dealt with.
All services have since returned to normal.
The incident is not being treated as suspicious and a file will be prepared for the coroner.
A spokesperson for British Transport Police said: “Officers were called to Sutton railway station at around 10.20pm yesterday (7 September) following reports of a casualty on the tracks.
“Paramedics also attended, however sadly a person was pronounced dead at the scene.
“The incident is not being treated as suspicious, and a file will be prepared for the coroner.”
A spokesperson for London Ambulance Service said: “We were called at 10.21pm on Sunday 7 September to reports of a person hit by a train at Sutton Railway Station, SM1.
“We sent multiple resources to the scene, including an ambulance crew, a paramedic in a fast response car, an incident response officer and paramedics from our hazardous area response team (HART).
“We also dispatched a trauma team in a car from London’s Air Ambulance.
“Very sadly, despite the best efforts of our crews, a person was pronounced dead at the scene.”
If you’ve been affected by what happened on the network today, there is always someone to talk to.
You can contact the Samaritans on 116 123 from any phone for a confidential chat.
